Why did he say "v'Im Nevi'im Hem"?
Malbim: Yirmeyah was told that also the remaining Kelim will be brought to Bavel. If so, it cannot be like they say, that the first ones will return!
What is the connection between having Devar Hashem and praying that the remaining Kelim not go to Bavel?
Malbim: [If Hashem spoke to them, surely] they heard oppositely, that the remaining Kelim will go to Bavel. If a Navi hears a decree, but was not told to inform others, surely this is so he will pray to nullify it! (If he was told to inform others, they must repent; his Tefilah will not help.)
What is the grammatical form of "Vo'u"?
Radak: It is a verb [in which the middle letter of the root is Vov], like "Mah Tovu Ohalecha Yakov" (Bamidbar 24:5), "Ki Oru Einai" (Shmuel I, 14:29). The past is used in place of the future. Vo'u applies to the Kelim, even though they cannot come by themselves without someone to bring them, like "Efod Yarad b'Yado" (ibid., 23:6), "Shavu Cheleihem Reikam" (above, 14:3).
Why does it say "u'Veis Melech Yehudah"?
Radak: This is like uv'Veis Melech Yehudah. The prefix Beis in "b'Veis Hashem" applies also to Veis Melech Yehudah.
